The present invention relates to an operating lever mechanism for an offset printing press.
Generally, an offset printing press includes a plate cylinder for mounting thereon a master plate, a blanket cylinder, an inking roller system and dampening roller system. In the dampening roller system, a fountain pan and a water applicator roller are provided so as to apply water in the pan to the plate cylinder by the applicator roller. U.S. Pat. No. 3,956,985 assigned to Ryobi. Ltd. (corresponding to Japanese Patent Publication No. 55-16069) discloses a single operating lever which is steppingly tiltable so as to control sequential printing operation starting from an ink application to the plate cylinder. More specifically, the operating lever is connected to an operation shaft which is stepwisely rotated about its axis upon steppingly tilting operation of the operation lever. The operation shaft is fixely provided with cams and arms those being mechanically associated with a form roller or an ink applicator roller, the plate cylinder, the blanket cylinder and a limit switch. Therefore, the rotations of the cams and movements of the arms will provide ON/OFF switching of the limit switch and will provide rotations of the plate and blanket cylinders and movement of the ink applicator roller.
However, according to this structure, the dampening system or water application system to the plate cylinder is continuously operated during actuation of the offset printing press, so that dampening liquid or water is always supplied from the fountain pan to the water applicator roller. As a result, excessive water may be applied to the plate cylinder, to thereby degrade printing quality at an initial stage of printing.
U.S. Pat. No. 4,676,156 discloses a dampening apparatus for a printing press in which an additional lever is provided so as to operate a dampening system independent of the manupulation to the operating lever which controls an inking system and main operation of the offset printing press.
However, according to the offset press, two levers must be manipulated, and therefore, high maneuverability may not be attainable, and it would be rather difficult to obtain optimum manipulation timings with resect to the two levers.